/*
 * cipher.c
 *
 * cipher meta-functions
 *
 * David A. McGrew
 * Cisco Systems, Inc.
 *
 */

/*
 *
 * Copyright (c) 2001-2006, Cisco Systems, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 *   Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 *   Neither the name of the Cisco Systems, Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "cipher.h"
#include "rand_source.h"        /* used in invertibiltiy tests        */
#include "alloc.h"              /* for crypto_alloc(), crypto_free()  */

debug_module_t mod_cipher = { 0, /* debugging is off by default */
"cipher" /* printable module name       */
};

err_status_t cipher_output(cipher_t *c, uint8_t *buffer,
        int num_octets_to_output) {

    /* zeroize the buffer */
    octet_string_set_to_zero(buffer, num_octets_to_output);

    /* exor keystream into buffer */
    return cipher_encrypt(c, buffer, (unsigned int *) &num_octets_to_output);
}

/* some bookkeeping functions */

int cipher_get_key_length(const cipher_t *c) {
    return c->key_len;
}

/*
 * cipher_type_self_test(ct) tests a cipher of type ct against test cases
 * provided in an array of values of key, salt, xtd_seq_num_t,
 * plaintext, and ciphertext that is known to be good
 */

#define SELF_TEST_BUF_OCTETS 128
#define NUM_RAND_TESTS       128
#define MAX_KEY_LEN          64

err_status_t cipher_type_self_test(const cipher_type_t *ct) {
    const cipher_test_case_t *test_case = ct->test_data;
    cipher_t *c;
    err_status_t status;
    uint8_t buffer[SELF_TEST_BUF_OCTETS];
    uint8_t buffer2[SELF_TEST_BUF_OCTETS];
    unsigned int len;
    int i, j, case_num = 0;

    debug_print(mod_cipher, "running self-test for cipher %s", ct->description);

    /*
     * check to make sure that we have at least one test case, and
     * return an error if we don't - we need to be paranoid here
     */
    if (test_case == NULL)
        return err_status_cant_check;

    /*
     * loop over all test cases, perform known-answer tests of both the
     * encryption and decryption functions
     */
    while (test_case != NULL) {

        /* allocate cipher */
        status = cipher_type_alloc(ct, &c, test_case->key_length_octets);
        if (status)
            return status;

        /*
         * test the encrypt function
         */
        debug_print(mod_cipher, "testing encryption", NULL);

        /* initialize cipher */
        status = cipher_init(c, test_case->key, direction_encrypt);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        /* copy plaintext into test buffer */
        if (test_case->ciphertext_length_octets > SELF_TEST_BUF_OCTETS) {
            cipher_dealloc(c);
            return err_status_bad_param;
        }
        for (i = 0; i < test_case->plaintext_length_octets; i++)
            buffer[i] = test_case->plaintext[i];

        debug_print(mod_cipher, "plaintext:    %s", octet_string_hex_string(
                buffer, test_case->plaintext_length_octets));

        /* set the initialization vector */
        status = cipher_set_iv(c, test_case->idx);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        /* encrypt */
        len = test_case->plaintext_length_octets;
        status = cipher_encrypt(c, buffer, &len);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        debug_print(mod_cipher, "ciphertext:   %s", octet_string_hex_string(
                buffer, test_case->ciphertext_length_octets));

        /* compare the resulting ciphertext with that in the test case */
        if (len != test_case->ciphertext_length_octets)
            return err_status_algo_fail;
        status = err_status_ok;
        for (i = 0; i < test_case->ciphertext_length_octets; i++)
            if (buffer[i] != test_case->ciphertext[i]) {
                status = err_status_algo_fail;
                debug_print(mod_cipher, "test case %d failed", case_num);
                debug_print(mod_cipher, "(failure at byte %d)", i);
                break;
            }
        if (status) {

            debug_print(mod_cipher, "c computed: %s", octet_string_hex_string(
                    buffer, 2 * test_case->plaintext_length_octets));
            debug_print(mod_cipher, "c expected: %s", octet_string_hex_string(
                    test_case->ciphertext, 2
                            * test_case->plaintext_length_octets));

            cipher_dealloc(c);
            return err_status_algo_fail;
        }

        /*
         * test the decrypt function
         */
        debug_print(mod_cipher, "testing decryption", NULL);

        /* re-initialize cipher for decryption */
        status = cipher_init(c, test_case->key, direction_decrypt);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        /* copy ciphertext into test buffer */
        if (test_case->ciphertext_length_octets > SELF_TEST_BUF_OCTETS) {
            cipher_dealloc(c);
            return err_status_bad_param;
        }
        for (i = 0; i < test_case->ciphertext_length_octets; i++)
            buffer[i] = test_case->ciphertext[i];

        debug_print(mod_cipher, "ciphertext:    %s", octet_string_hex_string(
                buffer, test_case->plaintext_length_octets));

        /* set the initialization vector */
        status = cipher_set_iv(c, test_case->idx);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        /* decrypt */
        len = test_case->ciphertext_length_octets;
        status = cipher_decrypt(c, buffer, &len);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        debug_print(mod_cipher, "plaintext:   %s", octet_string_hex_string(
                buffer, test_case->plaintext_length_octets));

        /* compare the resulting plaintext with that in the test case */
        if (len != test_case->plaintext_length_octets)
            return err_status_algo_fail;
        status = err_status_ok;
        for (i = 0; i < test_case->plaintext_length_octets; i++)
            if (buffer[i] != test_case->plaintext[i]) {
                status = err_status_algo_fail;
                debug_print(mod_cipher, "test case %d failed", case_num);
                debug_print(mod_cipher, "(failure at byte %d)", i);
            }
        if (status) {

            debug_print(mod_cipher, "p computed: %s", octet_string_hex_string(
                    buffer, 2 * test_case->plaintext_length_octets));
            debug_print(mod_cipher, "p expected: %s", octet_string_hex_string(
                    test_case->plaintext, 2
                            * test_case->plaintext_length_octets));

            cipher_dealloc(c);
            return err_status_algo_fail;
        }

        /* deallocate the cipher */
        status = cipher_dealloc(c);
        if (status)
            return status;

        /*
         * the cipher passed the test case, so move on to the next test
         * case in the list; if NULL, we'l proceed to the next test
         */
        test_case = test_case->next_test_case;
        ++case_num;
    }

    /* now run some random invertibility tests */

    /* allocate cipher, using paramaters from the first test case */
    test_case = ct->test_data;
    status = cipher_type_alloc(ct, &c, test_case->key_length_octets);
    if (status)
        return status;

    rand_source_init();

    for (j = 0; j < NUM_RAND_TESTS; j++) {
        unsigned length;
        int plaintext_len;
        uint8_t key[MAX_KEY_LEN];
        uint8_t iv[MAX_KEY_LEN];

        /* choose a length at random (leaving room for IV and padding) */
        length = rand() % (SELF_TEST_BUF_OCTETS - 64);
        debug_print(mod_cipher, "random plaintext length %d\n", length);
        status = rand_source_get_octet_string(buffer, length);
        if (status)
            return status;

        debug_print(mod_cipher, "plaintext:    %s", octet_string_hex_string(
                buffer, length));

        /* copy plaintext into second buffer */
        for (i = 0; (unsigned int) i < length; i++)
            buffer2[i] = buffer[i];

        /* choose a key at random */
        if (test_case->key_length_octets > MAX_KEY_LEN)
            return err_status_cant_check;
        status
                = rand_source_get_octet_string(key,
                        test_case->key_length_octets);
        if (status)
            return status;

        /* chose a random initialization vector */
        status = rand_source_get_octet_string(iv, MAX_KEY_LEN);
        if (status)
            return status;

        /* initialize cipher */
        status = cipher_init(c, key, direction_encrypt);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        /* set initialization vector */
        status = cipher_set_iv(c, test_case->idx);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        /* encrypt buffer with cipher */
        plaintext_len = length;
        status = cipher_encrypt(c, buffer, &length);
        if (status) {
            cipher_dealloc(c);
            return status;
        }
        debug_print(mod_cipher, "ciphertext:   %s", octet_string_hex_string(
                buffer, length));

        /*
         * re-initialize cipher for decryption, re-set the iv, then
         * decrypt the ciphertext
         */
        status = cipher_init(c, key, direction_decrypt);
        if (status) {
            cipher_dealloc(c);
            return status;
        }
        status = cipher_set_iv(c, test_case->idx);
        if (status) {
            cipher_dealloc(c);
            return status;
        }
        status = cipher_decrypt(c, buffer, &length);
        if (status) {
            cipher_dealloc(c);
            return status;
        }

        debug_print(mod_cipher, "plaintext[2]: %s", octet_string_hex_string(
                buffer, length));

        /* compare the resulting plaintext with the original one */
        if (length != plaintext_len)
            return err_status_algo_fail;
        status = err_status_ok;
        for (i = 0; i < plaintext_len; i++)
            if (buffer[i] != buffer2[i]) {
                status = err_status_algo_fail;
                debug_print(mod_cipher, "random test case %d failed", case_num);
                debug_print(mod_cipher, "(failure at byte %d)", i);
            }
        if (status) {
            cipher_dealloc(c);
            return err_status_algo_fail;
        }

    }

    return err_status_ok;
}

/*
 * cipher_bits_per_second(c, l, t) computes (an estimate of) the
 * number of bits that a cipher implementation can encrypt in a second
 *
 * c is a cipher (which MUST be allocated and initialized already), l
 * is the length in octets of the test data to be encrypted, and t is
 * the number of trials
 *
 * if an error is encountered, the value 0 is returned
 */

uint64_t cipher_bits_per_second(cipher_t *c, int octets_in_buffer,
        int num_trials) {
    int i;
    v128_t nonce;
    clock_t timer;
    unsigned char *enc_buf;
    unsigned int len = octets_in_buffer;

    enc_buf = (unsigned char*) crypto_alloc(octets_in_buffer);
    if (enc_buf == NULL)
        return 0; /* indicate bad parameters by returning null */

    /* time repeated trials */
    v128_set_to_zero(&nonce);
    timer = clock();
    for (i = 0; i < num_trials; i++, nonce.v32[3] = i) {
        cipher_set_iv(c, &nonce);
        cipher_encrypt(c, enc_buf, &len);
    }
    timer = clock() - timer;

    crypto_free(enc_buf);

    if (timer == 0) {
        /* Too fast! */
        return 0;
    }

    return (uint64_t) CLOCKS_PER_SEC * num_trials * 8 * octets_in_buffer
            / timer;
}
